JPH03226106A - Air-tight package for electronic component and piezoelectric vibrator using the same - Google Patents

Abstract

PURPOSE:To improve the shock resistance by specifying the length-to-width ratio and the length-to-thickness of a ceramic substrate and a ratio of the length to a thickness. CONSTITUTION:A ratio L/w of a length L to a width (w) of a ceramic substrate 2 is selected to be <=3 and a ratio L/t of the length L to a thickness (t) is selected to be 13 or below. When the thickness (t) of the ceramic substrate 2 is <=0.8mm (with side ratio L/t is <=15.6), damage or destruction is generated on a low melting point glass of a bonding face or the ceramic substrate 2. On the other hand, when the thickness (t) is >=1mm, even when a torsion or the bonding of the circuit substrate at shock is imparted directly, the brittle fracture is prevented by using the strength of the ceramic substrate 2 itself. Thus, the shock resistance is improved and the reliability is enhanced.

Description

Detailed Description of the Invention (Field of Industrial Application) The field of the present invention is an airtight container for electronic components and a piezoelectric vibrator using the same, and in particular a piezoelectric vibrator for surface mounting with good impact resistance. Regarding.

(Background of the Invention) Piezoelectric resonators, particularly crystal resonators, are useful as essential components for time or frequency reference sources, filter elements, and the like. In recent years, there has been a demand for surface mounting devices, as typified by chip devices such as resistors and capacitors. One such example is Utility Model Application Publication No. 1-81026 [Surface Mount Type Electronic Component] which has improved wlI resistance.

(Prior Art) No. 211 is an exploded perspective view of a crystal resonator illustrating such a conventional example.

The crystal oscillator is an ink piece 1. Ceramic substrate 2. It consists of a ceramic cover 3 and a bonding material 4. The crystal piece 1 is, for example, a rectangular AT-cut, and the counter electrode 4 has a drawer part extended at both ends.
form 15. Then, both ends are electrically and mechanically connected to the holding member 6 fixed to the conductive path 7a on the ceramic substrate 2. The conductive j17a extends to the back side through the through hole (Iff) through the path j17b +93
As shown in the figure, the external type 1i8, which becomes the external connection electrode (hereinafter referred to as external electrode) 8 (abcd), has a total area within 5 to 15% of the ceramic substrate 2, and the distance between each external electrode is The thickness shall be within 15 times the thickness of the ceramic substrate.

The bonding material 4 is made of low melting point glass and is covered with a ceramic cover 3. In such a device, the external electrode 8 was set as described above, so that leakage was prevented and W! It was confirmed that impact resistance could be improved. That is, it is possible to prevent damage to the low melting point glass on the bonding surface due to, for example, twisting or deflection of the circuit board caused by the ceramic substrate being rigidly fixed to the circuit board and directly subjected to vibrations and shocks.

(Problems with the prior art) However, although the crystal resonator with the above configuration has good impact resistance in a drop test of 10 cm onto a wooden board, local stress may be applied when there is a larger impact or when the impact occurs. In the case where a large amount of shock is concentrated, there is a problem in that it is not possible to achieve sufficient impact resistance only by improving the electrode structure as described above.

In particular, when stress is locally concentrated, not only the low melting point glass at the joint surface but also the ceramic substrate 2 itself may be destroyed due to its brittleness.

(Objective of the Invention) An object of the present invention is to provide a piezoelectric vibrator for surface mounting that has good RTW impact resistance and improved reliability.

(Points of Interest and Solution R) The present invention focuses on the relationship between the twisting/deflection of the circuit board during impact and the thickness of the ceramic substrate, and the dimensional ratio L/ of the length and width W of the ceramic substrate. While w is 3 or less, the dimensional ratio L/t of length L and thickness t is 13
The solution is to make it within the range. An embodiment of the present invention will be described below by taking a crystal resonator as an example.

(Example) FIG. 1 is a diagram of a crystal resonator, particularly a ceramic substrate, for explaining an example of the present invention. Note that explanations of the same parts as in the previous conventional example diagram will be omitted.

The crystal resonator is constructed by connecting both ends of a crystal piece 1 to a holding member on a ceramic substrate 2, as in the previous conventional example, and covering it with a ceramic cover 3 using low melting point glass as a bonding material (see above).
3Ili), however, the ceramic substrate or ceramic cover contains Al2O3 as the main component (90% by weight or more)A.
Let it be l. In this embodiment, the length L of the ceramic substrate 2 is 12°5 mm, and the length W is 5.5 mm.

However, the thickness is t. Further, the ceramic cover has a length of 12 mrn, a width of 4.8 mm, and a height of 1.7 mm.

Table 1 shows the thickness t of the ceramic substrate as 0. 6.0°8.1
．． 0 mm and shows the experimental results regarding impact resistance when stress is locally concentrated, that is, as shown in 2nd rM, the positioning protrusion is formed at constant 4! A crystal resonator 10 was attached to the i9, and a load needle 11 was dropped from 4 cm above the center of the ceramic substrate 2, and the state of damage at that time was examined. This is the result.

However, the load needle 11 is stopped by a stopper 12 and has a #113 diameter of 2 mm and a weight of 30 g.

Table 1 Thickness (mm) Number of failures/Number of tests Length L/Thickness tO, 6
10/10 20. 8 0, 8 10/10 15. 61,
OO/10 12-5 As is clear from this table, the thickness t of the ceramic substrate 2 is 0.
．． 8 mrn or less (side ratio L/t is 15.6 or less), all of which cause damage or destruction to the low melting point glass or ceramic substrate 2 on the bonding surface. On the other hand, when the thickness t is 1 mm or more, these problems are completely eliminated. In other words, at +1.0mm or more,
Even if the circuit board is directly affected by twisting and deflection when being hit with W, the strength of the 20 ceramic boards prevents it from breaking. In addition to this, its strength prevents deformation of the ceramic substrate itself, thereby preventing distortion from reaching the low melting point glass and preventing its breakage.

In addition, similar results were obtained in a drop test onto an iron plate from 1 m above.

For this reason, if the thickness t is less than 0.8 mm, airtight leakage will occur and it will become impossible to use, whereas if it is 1.0mm or more, there will be no airtightness leakage and the frequency will change over time. It is possible to improve reliability by improving characteristics.

(Other matters) In the above embodiment, it is assumed that the thickness of the substrate should be 1.0 mm or more, but the thickness is not limited to this, and due to the relationship of similarity,
The dimensional ratio L/w of the length L and width W of the ceramic substrate is approximately 2
3 to 3, basically the same effect can be achieved by setting L/t within 12.5 (see Chief 1), and within 13 taking into account the error. Also, since the smaller the shape is, the less likely it is to be damaged, the length L is 1.
A value of 5 mm or less is considered desirable. In addition, although the electronic components have been explained as crystal oscillators, they can of course also be applied to resistors, capacitors, etc. In short, surface mounting is made by bonding a ceramic substrate and a ceramic cover with low-melting glass to maintain airtightness. You can use it if you need it.

(Effects of the Invention) The present invention provides a dimensional ratio L between the length L and the width W of a ceramic substrate hermetically sealed with a ceramic cover and a low melting point glass.
/ w is set to 3 or less, and the dimensional ratio L/t of length L to thickness t is set to within 12.5, so the container for electronic components for surface mounting has good impact resistance and increased reliability. And a piezoelectric vibrator using the same can be provided.

[Brief explanation of drawings]

FIG. 111 is a diagram specifically showing a ceramic substrate for explaining an embodiment of the present invention. FIG. 112 is a diagram showing the impact test of the above example. FIG. 3 is an exploded view of a crystal resonator to explain a conventional example. FIG. 4 is a back view of the conventional example. Figure 1

Claims (3)

[Claims] (1) In an electronic component container for surface mounting in which a ceramic substrate on which an electronic element is attached and a conductive path is extended to the outer surface and a ceramic cover are bonded together using low melting point glass and hermetically sealed, the ceramic substrate An airtight container for electronic components, characterized in that the dimensional ratio L/w between the length L and the width w is 2 to 3, and the dimensional ratio L/t between the length L and the thickness t is 13 or less. . (2) A container for electronic components, characterized in that the length L is 15 mm or less. (3) A piezoelectric vibrator, characterized in that the electronic element is configured as a piezoelectric piece.